Fluid actuated stage control system with fluid flow readout signal

ABSTRACT

An arrangement for raising and lowering the various movable scenery settings of a theater stage by fluidic control systems. The actuators employed may be utilized as structural tie members providing lateral support for the building beam elements. The control system may be transferred between groups of actuators to economize on installation cost. Furthermore the control system selectively directs pressurized fluid into the actuators when raising or lowering the scenery settings and is provided with a readout system which is indicative of the rate of fluid flow into the actuators.

United States Patent Cruse [54] FLUID ACTUATED STAGE CONTROL SYSTEM WITH FLUID FLOW READOUT SIGNAL [72] Inventor: William M. Cruse, 333 North Norton Avenue, Los Angeles, Calif.

22 Filed: Dec. 18,1969

21 Appl.No.: 886,222

52 U.S.Cl. ..254/141,272/22,91/459, 254/93 R, 254/189, 137/568 51 1111.01. ..A63j1/02 [58] Field of Search ..272/22; 254/93 R, 141, 178, 254/189; 187/68, 70; 60/8, 51, DIG. 2; 185/33; 91/2, 3, 390, 459; 92/84, 137;

[56] References Cited UNITED STATES PATENTS 2,397,937 4/1946 Hadekel ..60/D1G. 2 X 722,597 3/1903 Lytton ..272/22 X 1,640,324 8/1927 Hibbard ..60/DIG. 2 X

[4 1 Oct. 10,1972

612,722 10/1898 Hall ..254/189 X 1,810,890 6/1931 Allen ..254/14] FOREIGN PATENTS OR APPLICATIONS 496,799 4/ 1930 Germany ..272/ 22 Primary Examiner-Richard C. Pinkham Assistant Examiner-R. T. Stouffer Attorney-Henry M. Bissell [5 7] ABSTRACT An arrangement for raising and lowering the various movable scenery settings of a theater stage by fluidic control systems. The actuators employed may be utilized as structural tie members providing lateral support for the building beam elements. The control system may be transferred between groups of actuators to economize on installation cost. Furthermore the control system selectively directs pressurized fluid into the actuators when raising or lowering the scenery settings and is provided with a readout system which is indicative of the rate of fluid flow into the actuators.

16 Claims, 6 Drawing Figures PATENTEDHBI 101912 3.697.047

sum 1 or 3 INVENTOR. WILLIAM M. CRUSE PATENTEDHBI 10 I972 3' 697' 047 SHEEI 2 nr 3 FIG.2

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@56 @(5l I 4 I F I G. 5

CABLE CABLE CABLE CYLINDER (BYLINDER CYLINDER P/C P C VALVE VA VE PULSE PULSE PULSE GEN. GEN. GEN.

48 L W '4E 1 T PUMP 64 UNIT .;1Z H 60 H REMOTE REMo' CONTROL CONT- L STA11'ION ST |o- FLUID ACTUATED STAGE CONTROL SYSTEM WITH FLUID FLOW READOUT SIGNAL BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to systems for controlling the movement and positioning of theater stage scenery, and more particularly, to such systems utilizing pressurized actuators controlled from a remote location.

2. Description of the Prior Art In theaters designed for the staging of theatrical productions, it is customary to provide movable stage scenery and equipment for moving such scenery into and out of the view of the audience. Typically, the scenery is raised or lowered when it is desired to remove it or bring it into view of the audience. This is customarily effected by hanging the scenery on horizontal suspension elements known as battens which are supported from cables running over pulleys to a master suspension control arrangement for that particular batten. Systems presently in use depend upon counterweights or winches which provide various disadvantages and limitations with respect to their operation.'Winch operation is sometimes undesirably slow, even when the winch is motor driven, and often cannot be used for scenery changes because it is not fast enough. With counterweights the batten travel is often undesirably limited by the available counterweight arbor travel. Sometimes stage pits are required in an attempt to extend the permissible arbor travel and also that of the scenery batten. Such arrangements require the provision of catwalks to accommodate the stagehands in the fixing of the counterweights, and the handling of such weights is necessarily a cumbersome procedure. Most important of all, however, all of the presently known scenery mounting systems place undesirable sideloads on the overhead support beams because of the weights involved and pulley arrangements which carry the cables across the structure to the side of the stage where the control portion of the system is located. Because of the loads involved, the theater building structure must actually be designed and strengthened to accommodate the special loads imposed by the stage scenery and the scenery moving systems. Counterweight systems require very costly lead weights and many extra catwalks from which the weights are loaded on to steel arbors or racks to counter the scenery load.

The roof beams toward the ceiling of the stagehouse are customarily and necessarily provided with side thrust bracing to take care of the necessary support Y required by the counterweight system. This is required because the counterweight is customarily equal to the weight of the scenery being supported. Accordingly, the additional load of the counterweights, transformed into side thrust loads by the pulley system, must be accommodated.

SUMMARY OF THE INVENTION It is another object of the present invention to provide a power control system for moving theater stage scenery with the control effcctuuted from u centralized remote panel.

Yet another object of the present invention is to provide a remote control system for moving theater stage scenery in which the necessary control equipment is minimized in order to reduce the cost of the system.

It is also an object of the present invention to provide a control system for moving theater stage scenery which is versatile and flexible in operation and can be handled by a minimum number of stage personnel.

In brief, particular arrangements in accordance with the present invention involve the use of actuator mechanisms known as cable cylinders which may be driven by a pressurized fluid medium to develop controlled bi-directional linear motion over a path of considerable'extent. Other types of actuators may be employed within the scope of the present invention, but fluid-driven cable cylinders are preferred because of their capability of developing a linear operating distance which is only slightly less than the overall length of a unit. The cable cylinders employed in preferred arrangements of the present invention consist essentially of a tube-like cylinder having a length corresponding to the desired output motion and containing a piston which is movable within the cylinder in either direction in response to pneumatic or hydraulic pressure applied to one side or the other of the piston. A looped cable extends outwardly through seals in opposite ends of the cylinder from fastenings on opposite sides of the piston. The cable passes over pulleys at opposite ends of the cylinder and returns in a path parallel to and outside of the cylinder. A load affixing element may be attached to the cable at any point along its external length. However for maximum effective operating distance, the load is connected to the cable at a point approximately halfway around the loop from the position of the piston in the cable loop. The cable is preferably provided with a smooth covering of a material such as nylon to protect against wear and to provide a suitable sliding seal through the bushings of the end caps of the cylinder. Cable cylinders of the type described are produced commercially by Tol-O-Matic, Inc. of Minneapolis, Minn.

In one particular arrangement in accordance with the invention, cable cylinders of the type described are supportably mounted on roof beams of the theater roof and fastened thereto in a fashion such as to provide lateral support and stiffening by virtue of the fact that the cable cylinders are tied into the stagehouse structural steel members. 96 such cylinders are mounted side by side in this fashion, spaced on 6 inches centers with a portion thereof on 1 ft. centers. Associated with each cable cylinder is a group of loftblocks, individually carrying cables fastened to a scenery batten, the position of which is to be controlled by the associated cable cylinder. With each individual cable cylinder-loftblock combination, there is provided a headblock containing a sheave for each of the loftblocks of a given set. Cables from each of the loftblocks run over the sheaves of the associated headblock and are ganged to a cleat which is affixed to the cable of the associated cable cylinder. Thus, actuation of a given cable cylinder is effective, by means of this arrangement, to either raise or lower the associated batten and the scenery attached thereto, or to support the batten in a predetermined position as desired.

Associated with each cable cylinder in this arrangement is a counterbalance valve which serves to admit pressurized fluid to one end or the other of the cylinder upon the application of pressurized fluid above a preset threshold level. Thus the cable cylinder is maintained fixed in a given position until fluid at a pressure above the threshold level is applied to the associated counterbalance valve. The cable cylinders are driven by a remote control unit basically comprising a power unit consisting of a motor and pump and associated control apparatus. The remote control units are arranged so as to be transferrable from one or a block of the cable cylinders to another one or another block of cable cylinders, thus permitting control of the 96 cylinders by a lesser number of remote control units. In one particular arrangement in accordance with the invention, six such remote control units are provided inan installation having 96 cable cylinders with eachcontrol unit being coupleable to any cable cylinder. When a cable cylinder and counterbalance valve combination is uncoupled from a remote control unit, the counterbalance valve maintains the fluid pressures static within the cable cylinder, thus holding its position until the remote control unit is again coupled thereto to drive the cable cylinder actuator to another position.

Each of the remote control units utilized in this particular system in accordance with the invention includes a motor and pump coupled to drive a pressurized fluid when the motor is actuated, together with suitable equipment for energizing the motor to operate at a selected one of a number of suitable speeds in either rotational direction, and equipment for indicating the speed and direction of motion of the scenery being driven by the associated cable cylinders. In accordance with an aspect of the invention, the fluid flow path of the remote control unit coupled to a given cable cylinder is provided with a fluid driven pulse generator which serves to generate a series of electrical pulses at a rate corresponding to fluid flow. These pulses are preferably generated at intervals corresponding to the motion of the cable cylinder in 1/16 inch increments. The speed and direction of motion of the cable cylinder may be set in accordance with an aspect of the invention by various controls on a panel of the remote control unit. Provision is also made in accordance with a further aspect of the invention for an automatic change of speed when the scenery being moved by the cable cylinder reaches a first position with further movement of the scenery being controlled at a lesser speed until the scenery reaches a second preset position at which it is stopped and maintained in position. The position of the scenery associated with a given cable cylinder to which a remote control unit is coupled at any given time is indicated to the operator by means of a visual readout measured in sixteenths of an inch from a reference position.

Another particular arrangement in accordance with the invention utilizes a type of valve known as a proportional control valve in conjunction with each cable cylinder on a one-for-one basis. A common pump unit comprising a motor, pump, reservoir, pressure regulator, etc. is connected to all of the proportional control valves which selectively direct pressurized fluid to an associated cable cylinder in response to electrical signals from a remote control station. The remote control stations are arranged to be switched electrically from one proportional control valve to another as desired, with 24 such stations being provided to control 96 cable cylinders. This arrangement is similar to the arrangement described hereinabove, the principal difference being the manner of switching the remote control stations so as to provide selective control of the cable cylinders. In this arrangement it is done by means of electrical switching devices, whereas in the first described arrangement the switching is by means of transferring the couplings to the hydraulic lines leading to the cable cylinder and valve units.

BRIEF DESCRIPTION OF TI-IEDRAWING A better understanding of the present invention may be had from a consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is an elevational view of one particular arrangement in accordance with the invention for controlling stage scenery;

FIG. 2 is a plan view of a portion of the arrangement of FIG. 1 showing further details thereof;

DESCRIPTION OF THE PREFERRED EMBODIMENTS As represented in FIGS. 1 and 2, the structural portion 10 of particular arrangements in accordance with the invention may comprise a batten l2 suspended from cables 14 which extend over a plurality of loftblocks 16 and headblocks 18 for coupling to a cable cylinder 20. The cable cylinder 20 is shown suspended from structural beams such as 22 which form a part of the skeletal structure supporting the building. As may be seen in FIG. 2, each cable cylinder such as 20 is tied in to each of the beams 22 and serves as an orthogonal support member for strengthening the skeletal structure against side thrust forces. It will be understood that the scenery of the theater is suspended from the battens 12, there being a sufficient plurality of battens l2 and associated arrangements comprising the cables 14 and the cable cylinders 20 to accommodate all of the various pieces of scenery on the stage. In this particular arrangement of the invention, all of the cables 14 from a given individual batten 12 are carried together around a multiple-sheave pulley of a single headblock 18, from whence they extend to a cleat 24 which is affixed to the cable 26 of the cable cylinder 20. Thus all of the cables 14 of a given unit are driven in unison to raise or lower the batten 12. FIG. 2 shows a second cable cylinder 21, a second 'cleat 25, and a plurality of cables 15 extending from a headblock 19 and loftblocks 17 making up a second such system. Additional cable cylinders 20a,

b, etc. are shown without the cable and block portions of the individual systems, which have been omitted for simplicity. It may be seen that such an arrangement provides substantial lateral support for the beams of the building support structure.

FIG. 3 shows the details of the construction of an individual cable cylinder, and depicts a cable cylinder 20 comprising a cylinder 31 extending between a pair of pulley units 32 around which a cable 26 extends from the opposite faces of an internal piston (not shown) to the cleat 24. A pair of tubes 34 extend from opposite ends of the cylinder 31 and serve to admit or release pressurized fluid to or from the cylinder 31 to produce linear movement of the cleat 24 and the associated cables 14 affixed thereto. For example, the application of pressurized fluid to the left-hand tube 34 results in a movement from left to right of the piston within the cylinder 31, resulting in a corresponding movement of the cleat 24 from right to left, thus pulling the cables 14 which would raise the batten 12 (FIG. 1 Similarly, application of pressurized fluid via the right-hand tube 34 results in motion of the piston inside the cylinder 31 from right to left and a corresponding motion from left to right of the cleat 24 and the system comprising the associated cables 14.

FIG. 4 illustrates in block diagram form one particular system in accordance with the invention which is provided for. operating the structural arrangements of FIGS. 1 and 2. As shown in FIG. 4, each cable cylinder is associated with a counterbalance valve 42 (C/B valve). The counterbalance valves 42 are of a type which acts like a two-way check valve having a preselected release threshold. This threshold is selected so that the cable cylinder 20 together with the scenery load associated therewith is held in a static position until sufficient pressure is applied to the counterbalance valve 42 to override the check threshold and drive the cable cylinder 20 in one direction or the other. The system 40 includes a plurality of remote control stations 44, each having associated therewith a pump unit 46 and a pulse generator 48. The pump units 46 may be coupled and uncoupled with the various counterbalance valves 42 as indicated by the arrow symbols associated with the dashed line 49. I

In systems of the kind described herein, it is preferred to use hydraulic fluid rather than air for the operating fluid applied to the cable cylinders 20. It is considered that this provides a safer, more reliable system with greater protection against leaks or other causes of failure and a greater likelihood that small leaks may be discovered. The system 40 of FIG. 4 is of a type which is more suitable for smaller and less costly installations, such as may be employed in high school auditoriums and the like. The pressure lines 52 from a given pump unit 46 may be coupled to any one of the counterbalance valves 42 by means of so called quickdisconnect couplings to control the actuation of any one of the plurality of cable cylinders 20. In one particular system in accordance with FIG. 4, 96 cable cylinders 20 are provided together with 12 remote control stations 44. The remote control stations 44 are capable of connection to any one of the cable cylinders 20 via the associated counterbalance valve 42 in the manner indicated so as to provide added versatility in control of the cable cylinder units without the necessity 6 for completely duplicating the remote control stations 44.

FIG. 5 illustrates a particular remote control station 44 for use in the systems depicted in FIGS. 4 and 6. As shown in FIG. 5, the station comprises a control mode selector switch 51, a speed indicator 53, a bidirectional counter having a primary preset stage 54 and a secondary preset stage 55, a manual speed control potentiometer 56, a preset speed control potentiometer 57, a speed control lever 58, and a position readout 59. The control mode selector switch 51 is used to select between the manual speed control 56 and the preset speed control 57 as to which of the two is controlling. When the control mode selector switch 51 is in the manual mode position, the associated pump unit 46 (FIG. 4) is driven in accordance with the speed setting of the manual speed potentiometer 56. The control lever 58 is placed in the up or down position to cause the pump unit 46 to be energized to drive the scenery up or down and is moved to a neutral position to discontinue the drive from the pump unit 46. The speed meter 53 is calibrated from 0 to 300 feet per minute and is used to provide the operator with an indication of the speed of movement of the particular scenery being controlled by the station 44. The readout portion 59 is arranged to provide an indication of the actual location of the scenery to which the station 44 is coupled, and provides such an indication in multiples of 1/16 inch. This is effected by means of a Nixie tube display. There is also an indication of plus or minus corresponding to whether the motion is in the up or down direction.

When the speed control mode selective switch 51 is in the preset mode position, operation of the cable cylinder unit to which the station 44 is coupled is under the control of the preset stages 54 and 55 of the bidirectional counter, together with the preset speed control 57. These two stages are set by the operator to predetermined positions, expressed in 1/16 of an inch, at which the drive shifts from full speed of 300 feet per minute (5 feet per second) to a reduced speed selected by the preset speed control 57, after which the motion continues at this reduced speed (typically for the last 5 feet) until the point designated by the primary preset 54 is reached. At this time the motion stops. Suitable relay circuitry (not shown) is included in the control station 44 to effectuate the change of speed at the secondary preset point and the stopping of motion at the primary preset point when operation is in the preset speed mode.

Signals in the form of repetitive pulses corresponding to incremental movements of 1/16 inch are applied to the remote control station 44 from a pulse generator 48 coupled to the pump unit 46 (FIG. 4). This pulse generator is preferably a vane-type turbine mounted in the fluid flow path of the pump unit 46 and having a shaft output driving a pulse generating tachometer. Altematively, it may be a mechanically driven tachometer coupled directly to the cable cylinder 20. In the latter case, however, a larger number of pulse generators would have to be provided in order to have an individual generator associated with each cable cylinder unit.

FIG. 6 represents a block diagram of another system 60 in accordance with the present invention which is preferred for use in larger, more elaborate installations such as might be employed in the largest commercial theaters. In one such system, 24 remote control stations 44 were employed in conjunction with 96 individual cable cylinders 20. Such a system corresponds to one in the prior art employing 24 stagehands to control the stage scenery, a number which is adequate to take care of every foreseeable contingency.

As shown in FIG. 6, the system 60 comprises a plurality of cable cylinders 20, each of which is connected to a proportional control valve 62 (P/C valve) which is provided with its own separate pulse generator 48. In the system 60, a central pump unit 64 is employed comprising a motor, pump, reservoir, pressure regulator and the like of sufficient capacity to drive the cable cylinders 20 which may be operated simultaneously under the control of one or more of the remote control stations 44, to which they are coupled. In the system 60, the remote control stations 44 may be transferred by electrical switching circuitry of a type known in the telephone art, for example, to selected ones of the proportional control valve 62-pulse generator 48 combinations, as is indicated by the arrow symbols associated with dashed line 65. In this particular system, it is feasible and preferable to employ a pulse generator 48 having the capability of storing the position of the cable cylinder 20 with which it is associated. Thus, when a given remote control station 44 is connected to a specific pulse generator 48, the position of the associated cable cylinder 20 and scenery controlled thereby thus stored in the pulse generator 48 is transferred to the indicating unit 59 of the remote control station 44 so as to immediately provide a display of the existing position of the associated scenery and cable cylinder 20coupled thereto. In a system of the type shown in FIG. 4, this is not feasible where the pulse generator 48 is transferable with the remote control station 44, and thus it is necessary for the operator to make a note of the position of each cable cylinder 20 as the remote control station 44 is shifted from one cable cylinder to another, as well as to set into the display 59 the existing position of the scenery controlled by the particular cable cylinder 20 to which the remote control station 44 is being coupled.

The proportional control valves 62 of the system 60 depicted in FIG. 6 are preferably of an electro-hydraulic type known as pilot operated, 4-way, sliding spool valves. These provide output hydraulic flow in proportion to an input electrical signal and may be used on closed-center hydraulic systems with pressures up to 3,000 psi. One suitable type is the Moog Series No. 60, available commercially from Moog Inc. Industrial Division, East Aurora, NY. In the system 60 of FIG. 6, for use in conjunction with the proportional control valve 62 as just described, the control stick 58 (FIG. 5) provides control of a rheostat connected between the positive and negative terminals of a low voltage DC power supply. Such control units may be obtained from Moog Inc. Industrial Division, identified above. As used in the manual speed mode in the remote control station 44 in the system 60 of FIG. 6, the manual speed control 56 is connected to adjustably vary the DC voltage that is available for application to the rheostat controlled by the stick 58, so that the stick 58 may be used to adjust the speed of an associated cable cylinder 20 within the limits set by the manual speed control 56.

There have thus been described particular systems in accordance with the invention for providing automatic control of scenery positioning arrangements for theater stages. Such systems not only improve the movement of scenery by doing it more smoothly, quickly, safely, and precisely, but also accomplish this with automatic control whereby the operator need only select a particular position for the scenery to be moved, and it is relocated by the automatic control equipment. Systems in accordance with the invention advantageously eliminate the need for heavy counterweights, which are expensive and also add substantially to the weight which must be supported by the scenery support structure. In addition the equipment of the invention in accordance with an aspect thereof is built in as part of the building structure in a manner such as to provide lateral support for the structure, thus decreasing the necessity for special structural support members.

Although there have been described above specific arrangements of a scenery control system in accordance with the invention for the purpose of illustrating the manner in which the invention may be used to advantage, it will be appreciated that the invention is not limited thereto. Accordingly, any and all modifications, variations, or equivalent arrangements which may occur to those skilled in the art should be considered to be within the scope of the invention.

What is claimed is:

l. A stage scenery control system comprising:

pressurized fluid responsive actuator means coupled to support an item of stage scenery;

valving means coupled to control the flow of fluid to said actuator means, said valving means having a controllable variable flow condition and a fluid blocking condition for locking the actuator means in a fixed position;

means associated with said valving means for providing a readout signal indicative of the rate of flow of fluid to said actuator means;

a source of pressurized fluid coupled to said valving means; and

remote control means for switching the valving means from the condition of fluid blockage to the variable flow condition in which fluid is passed to said actuator means at a selected rate of flow to produce a selected movement of the stage scenery, the remote control means including means for selectively controlling the direction and rate of fluid flow through the valving means in accordance with the readout signal.

2. A system in accordance with claim 1 wherein said valving means comprises a counterbalance valve having a threshold range blocking the flow of fluid therethrough in either direction for pressures below a predetermined threshold level and permitting the flow of fluid therethrough at pressures above said predetermined threshold level.

3. A system in accordance with claim 1 wherein said valving means comprises a proportional control valve having an operating characteristic in which fluid is blocked in the absence of a control signal thereto and wherein fluid is passed in one of two directions to flow therethrough in response to the application of an electrical signal of one of two polarities.

4. A stage scenery control system in accordance with claim 1 comprising:

a first number of actuator means;

a second number of remote control means, said second number being less than said first number; and

means for selectively connecting any one of said remote control means with any one of said actuator means in order to provide for operative coaction of the actuator means and control means in combination.

5. A system in accordance with claim 4 wherein the means for selectively connecting a control means to an actuator means comprises releasable fluid coupling means.

6. A system in accordance with claim 4 wherein the means for selectively connecting a control means to an actuator means comprises electrical switching means.

7. A system in accordance with claim 4 wherein each actuator means comprises a cable cylinder having an external cable movable along substantially its entire length, a cleat affixed to the cable, and a plurality of cables extending from said cleat through a plurality of pulleys to the corresponding scenery support.

8. A system in accordance with claim 4 wherein said actuator means comprise elongated structural members mounted to provide support for the stage scenery control system.

9. A system in accordance with claim 8 located within a building having roof trusses, wherein each actuator means comprises a cable cylinder extending substantially orthogonally to the roof trusses of the building, and further including means for fastening each of said cable cylinders to the respective roof trusses of the building.

10. A stage scenery control system comprising:

a plurality of fluid actuated linear driving means;

a plurality of individual stage scenery supports, one

for each of said driving means;

a cable system including a headblock and a plurality of loftblocks for attaching a support to a corresponding driving means, each support being affixed to at least two cables of said cable system;

a lesser plurality of remote control stations for applying pressurized fluid to said driving means, at least one of said control stations including a display means for indicating the position of the driving means, first presettable means for arresting the flow of fluid to the driving means at a predetermined position of the associated support, and speed control means for selecting the speed of motion of the driving means; and

means for selectively coupling one of said control stations to a selected one of the driving means to provide for the actuation thereof by the control station.

11. A system in accordance with the claim 10 wherein the remote control station includes second presettable means for reducing the speed of motion of the driving means at a predetermined position.

12. A system in accordance with claim 11 wherein the remote control station further includes speed indicating means for indicating the speed of movement of the driving means.

13. A system in accordance with claim 12 further including presettable speed control means, manual speed control means and a control mode selecting switch for selecting between the preset and manual speed control means.

14. A system in accordance with claim 13 further including a control stick operative in the manual speed control mode for selectively varying the flow of fluid to the driving means.

15. A system in accordance with claim 12 further including means coupled to the fluid actuated driving means for developing an electrical signal proportional to the flow of fluid therethrough, and means coupling said electrical signal to the remote control station to provide an indication of the speed of movement in response thereto.

16. A system in accordance with claim 15 wherein said signal comprises a plurality of sequential pulses having a repetition rate proportional to fluid flow and further including means for applying said pulses to the display means. 

1. A stage scenery control system comprising: pressurized fluid responsive actuator means coupled to support an item of stage scenery; valving means coupled to control the flow of fluid to said actuator means, said valving means having a controllable variable flow condition and a fluid blocking condition for locking the actuator means in a fixed position; means associated with said valving means for providing a readout signal indicative of the rate of flow of fluid to said actuator means; a source of pressurized fluid coupled to said valving means; and remote control means for switching the valving means from the condition of fluid blockage to the variable flow condition in which fluid is passed to said actuator means at a selected rate of flow to produce a selected movement of the stage scenery, the remote control means including means for selectively controlling the direction and rate of fluid flow through the valving means in accordance with the readout signal.
 2. A system in accordance with claim 1 wherein said valving means comprises a counterbalance valve having a threshold range blocking the flow of fluid therethrough in either direction for pressures below a predetermined threshold level and permitting the flow of fluid therethrough at pressures above said predetermined threshold level.
 3. A system in accordance with claim 1 wherein said valving means comprises a proportional control valve having an operating characteristIc in which fluid is blocked in the absence of a control signal thereto and wherein fluid is passed in one of two directions to flow therethrough in response to the application of an electrical signal of one of two polarities.
 4. A stage scenery control system in accordance with claim 1 comprising: a first number of actuator means; a second number of remote control means, said second number being less than said first number; and means for selectively connecting any one of said remote control means with any one of said actuator means in order to provide for operative coaction of the actuator means and control means in combination.
 5. A system in accordance with claim 4 wherein the means for selectively connecting a control means to an actuator means comprises releasable fluid coupling means.
 6. A system in accordance with claim 4 wherein the means for selectively connecting a control means to an actuator means comprises electrical switching means.
 7. A system in accordance with claim 4 wherein each actuator means comprises a cable cylinder having an external cable movable along substantially its entire length, a cleat affixed to the cable, and a plurality of cables extending from said cleat through a plurality of pulleys to the corresponding scenery support.
 8. A system in accordance with claim 4 wherein said actuator means comprise elongated structural members mounted to provide support for the stage scenery control system.
 9. A system in accordance with claim 8 located within a building having roof trusses, wherein each actuator means comprises a cable cylinder extending substantially orthogonally to the roof trusses of the building, and further including means for fastening each of said cable cylinders to the respective roof trusses of the building.
 10. A stage scenery control system comprising: a plurality of fluid actuated linear driving means; a plurality of individual stage scenery supports, one for each of said driving means; a cable system including a headblock and a plurality of loftblocks for attaching a support to a corresponding driving means, each support being affixed to at least two cables of said cable system; a lesser plurality of remote control stations for applying pressurized fluid to said driving means, at least one of said control stations including a display means for indicating the position of the driving means, first presettable means for arresting the flow of fluid to the driving means at a predetermined position of the associated support, and speed control means for selecting the speed of motion of the driving means; and means for selectively coupling one of said control stations to a selected one of the driving means to provide for the actuation thereof by the control station.
 11. A system in accordance with the claim 10 wherein the remote control station includes second presettable means for reducing the speed of motion of the driving means at a predetermined position.
 12. A system in accordance with claim 11 wherein the remote control station further includes speed indicating means for indicating the speed of movement of the driving means.
 13. A system in accordance with claim 12 further including presettable speed control means, manual speed control means and a control mode selecting switch for selecting between the preset and manual speed control means.
 14. A system in accordance with claim 13 further including a control stick operative in the manual speed control mode for selectively varying the flow of fluid to the driving means.
 15. A system in accordance with claim 12 further including means coupled to the fluid actuated driving means for developing an electrical signal proportional to the flow of fluid therethrough, and means coupling said electrical signal to the remote control station to provide an indication of the speed of movement in response thereto.
 16. A system in accordance with claim 15 wherein said signal comprises a plurality of sequential puLses having a repetition rate proportional to fluid flow and further including means for applying said pulses to the display means. 